It is to be noted that, although the present invention has been explained below whilst referring to a functional fluid for particular use as a marine cylinder oil, the present invention is not limited in any way to such a marine cylinder oil; the present invention can be equally applied to lubricating composition intended for other applications.
Marine cylinder oils used in marine diesel engines are subject to particularly high levels of stress due to the fact that marine diesel engines are usually run continuously at near full load conditions at high temperatures and pressures for long periods of time.
Marine cylinder oils are so-called “total loss” compositions and their purpose is to provide a strong oil film between the cylinder liner and piston rings. If the oil film breaks down under the high operating temperatures and pressure, the internal walls of the cylinder will be subjected to adhesive wear (known as “scuffing”).
Apart from providing a strong oil film between the cylinder liner and piston rings, the marine cylinder oil is typically formulated to provide for good oxidation and thermal stability, water demulsibility, corrosion protection and good antifoam performance.